In a gun having a breech locking barrel which requires, because of its overall design, a trigger bar to be positioned above the pivot pin of the trigger, a problem often occurs in avoiding interference between the trigger bar and the cam of the barrel when compact positioning is an objective of the design. An improved design for the camming lug of the barrel and optimum positioning of the trigger bar with respect to the trigger are areas where improvements can be made.
One area in which compactness of a handgun can be achieved relates to how closely the trigger assembly and the barrel can be positioned relative to each other. When a breech-locking barrel is used and the trigger bar is positioned above the pivot pin of the trigger, the trigger, the trigger bar and the barrel must be arranged so that interference cannot occur between the trigger, the trigger bar and the barrel, because of the movement of the intervening cam element enabling rotation of the barrel between its locked and unlocked positions. Such a handgun usually has a relatively high profile, the barrel being positioned a substantial distance above the trigger guard and handle or pistol grip.
In order to provide compactness generally in a handgun, others have devised various designs. For instance, U.S. Pat. No. 1,618,310 to Browning teaches the use of an annular flange to guide the barrel at its forward end, and the cooperation between a cam groove and a fixed part of the firearm frame to receive the barrel lug, at the rear end. Thus, Browning provides a stepped structure to achieve compactness and efficiency of design, but does not teach a camming mechanism structure similar to the present invention. Likewise, U.S. Pat. Nos. 2,664,786 and 4,854,217 of Guisasola and Ranson, respectively, teach lock mechanisms for the barrel of a gun, but do not teach a similar camming mechanism design, as with the present invention, to achieve compactness and efficiency.